Method of electric welding.



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Io Drawing.

To all whom it may concern:

5 State of I ew York, have invented a'cer'ta-in new and useful Improvement in Methods of Electric Welding, of which the following is a s ification.

be invention is an improvement in the art of electrical welding, whereby olution of continuity of the metal at the weld is avoided, and the strength of the material at the weld is rendered equalto that of the material elsewhere. 7

.As commonly practised, electrical ,welding is a sticking together of the o posing bodies by rendering t and pressing them into more or less close contact. The result is attraction between the molecules at the surfaces of the respective bodies, caused first by renderingsaid molecules mobile by heat, and: then moving them by the'pressure into closer proximity and so into theirfields of mutual attraction. In old While te perature'of a degree suiiicient to make the opposing surfaces adhesive will eflect a union, the'strength of. said union-is a matter of ,Wide variation. In fact the strength of any particular joint cannot be known. except, by testing "that particular joint to destruction norfrom the tests of one joint can" the strength of other joints cer-, tainl-ylbe inferred. A given joint'may bej ampllystrong to meet conditionsinvolvin .smal strain, as, for exa 'ple, theunitin'g o :electrical line conductors or the parts of utensils or light structures, but it may be 7 40 whollyinadegpateto withstand the demands of heavy 10a chinery.

to moderately increasing current-strength,

'of obtaining greate lasticity or uidlt'y of the metal e m t Increase of ressure' leads-to greater extrusipn of meta at the joint which is intensified cwhen the fluidity or plasticity of the metal a is augmented. The result is then merely surface 'fadhesiomas before, over a, larger area. To increase the duration of the curphysical condition of the metal itself.

Specification of Letters Iatent Application fled rebmar e, 1918. Serial llo. 215,110.

the currentmay burn olf-t e protu eir surfacesp astic'or pasty physical nomenclature, the surfaces are then, said to f adhere. T

or shocks or of moving mai 1 withQa current of fiv'e' hundred and severity.

The effort-to make stronger jointshas led- .or both current strength and current dura-.

r butthis Patented Oct. 15,1911;

Another cause of uncertaint and unrelia- -b1l'1ty of the welded joint is t e great difliculty, and often practical im ossibility, of

msurm ,a uniform current ow per unit' area 0 welding surface. If through the presence of other materials in the m etal, especially substances of lower conductibilits, the current" will cause unequal heating 0 the surface, with a result that one part may be burned before'a proper plastic condition is produced elsewhere. Soalso ifthe surfaces exhibit protuberances which make contact before the more do ressed rtion's, rances before thelast-named portions are suitably heated, or even if the opposed surfaces are not rigorously parallel, the current 'will become concentra and so afiect the portions of said surfaces which-first make contact.

Increasing the current to obtain greater plasticity, or continning'itfor longer peri- PATENT ,:;..Fm.

ods, or using'grea'ter mechanical pressure i does not overcome these. difficulties. l

I, hayekdiscovered, after much study and research, that I can-produce an electrically weldedunion possessing a strength as great as thatof an integral mass of the same inaterial of like-cross sectional area by subjecting the bodies to be'weld'ed to an electrical current of extremely and abnormally hi [1 i am re strength'existing fora very brief perifd' of time. Where the area is small,

say about five square inches or under, I prefer'to use currents ofabout five thousand airperes. to the square inch," but I. have used,

and am now practically using in commercial workcurrents.'of over thirty thousand amperes per square-inch ofsurfacecontact be- J "actually welding steel bodies ,whereoflthe tween the'welded steel bodies. Thus I. am

areaof contact is nineteen squareinches *two to three-seconds, I- am not-aware 'of I05 rents have 'beeuused in anyelectricalI-weld- 1 any instance in the'prior art where-such curing operation, or that any. knowledge exists as to their properties, ,as herein set forth. 4

."lhe weld is caused by surface molecular'attraction or adhesion, but by a complete dissociation of the molecules for a cere- 10o" be about s tain distance inward from the sprface of each body, followed by the intermingling of the molecules of one body with those of the other, and their mutual attraction developed within the momentarily gaseous film, so that the said molecules become united throughout the mass. Under The old physical nomenclature, they cohere. If the two bodies are of the same material, then after welding there is no solution of continuity, and the two bodies simply become integrally one body. If the two bodies are of different materials. then while there is still, no solution 'of continuity, a portion of the welded mass is composite and partakes' 'of'the nature of both bodies; that is to say, if, for example, copper and zinc be the materials, a portion of the welded mass will be an alloy or mixture of the two metals.

The enormouslyhigh temperature developed gasifies the metal or metals of the bodies instantly, and in the brief time period permit-ted .the molecules to intermingle as anywhere else.

and cohere- With such ampere strengths there is no time for any -=burning of the metal or for the conduction of heat away through the mass-before the gasification of the metal and the interminglin'g of molecules occurs. Of course, the temperature is far above that which would permit the metal to become plastic or pasty. Because there is complete "cohesion of the molecules within the mass the physical condition of the metal is the-same at the place of union Therefore the same strength everywhere follows as "a necessary consequence. This can be accomplished in no other way, so far as I know.

When currents of such extreme ampere strength are used, as before. noted, all the difliculties incident to. surface irregularities, lack of parallelism" and difference of condutib'ility of different portions disappear, and-naturally so since the intermingling produced is of gases in which the mole- ,cules are free and comparatively widely separated. So also'there appears to be no limitation of surface areas which can be united. lVith asuitably strong momentary current it is as easy to weld areas of say twenty square inches as areas of one square inch.

Another adva-nta eous result attending my use of enormous y 'stron current is the neutralization of the iflicu ties due to radiation from theaheatedbodies to the hold ing electrodes when the area of contact between said bodies and said electrodes is largely increased. To take a simple illustration: Assume that two bars measuring- 1n rectangular cross sectlonal areaone square inch are to be united. The best conditions 'are attained when each bar is inclosed in a copper electrode in contact with all four sides. If each electrode is one inch in width, then the contact area of each electrode with its bar is four square inches. As already pointed out, I can butt-weld these bars by my process and be certain thatthe strength at the union will be equal to that of the integral metal. Suppose, however,

of that area be changed, as,, to illustrate, let the surface area instead of one square inch in the shape of a rectangle be changed to while keeping the area the same, the'form one square inch-in the form' of a paralleloradiation surface 'of the copper electrode holders will then be five inches instead of four inches, or twenty per cent. greater.-

gram of 0. 5k2- inches. .llhe contact area or This'is increased radiation surface of the bar, and, therefore, the heat developed will escape to the electrode more rapidly than before. This loss is, as I have stated, easily counteracted by an increase in the ampere strength of the current.

I claim:

1. The improre'mentin the art of electric I welding, which consists in subjecting the bodies to bejunited to a current of extremely high ampere strength and of very brief duration, whereby said bodies are caused to form a single homogeneous bodywithout solut-ion of continuity. '2. The improvement in the art of electric welding,- which'consists in'su'bjecting the bodies to be united to a. current of extremely h and of very brief high ampere stre duration, and there y producing molecular dissociation at each of theopposing faces of said bodies and an intermingli of the dissociated molecules, wherebysai bodies body without solution of continuity.

3. The improvement in the art of electric welding, which consists in subjecting two bodies of respectively ifl'erent metals to a current of extremely high ampere stren h i and very brief duration, and thereby pr ucing molecular dissociation at each ofthe op posi faces of said bodies and an interming mg of the are caused to form a single homogeneous dissociated molecules, whereby said bodies are caused to form an integral body without solution of continuity,

a part of said body being-composed of a. '-mixture or alloy of the materialsof two ori 'nal bodies.

n testimony whereof I have-allixed my signature in presence of two witnesses.

Witnesses .Gnm'aunu T. Poms, Max T. McGARmr'.

THOMAS E. MURRAY, R. 

